Commonly, an electrical load receives power from a remote power supply. A cable is used to electrically connect the power supply with the load in order for the current from the power supply to reach the load. When the current is AC (alternating current) the ideal waveform of the voltage is essentially sinusodial with a desired amplitude at the load. However, the use of a cable to electrically connect the power supply and the load results in a voltage drop across the cable due to the impedance of the cable. Existing line voltage regulators compensate for this voltage drop that exists across the cable typically by sensing the voltage drop across the cable at the load and subtracting the voltage drop from the voltage regulator output voltage feedback signal. In this way a desired voltage is provided at the load and the voltage is considered regulated.
Moreover, if the load is nonlinear, distortion voltage, which is also known as the harmonic part of the voltage, is introduced into the voltage provided by the power supply at the load and distorts the sinusodial waveform. Heretofore, there are no line voltage regulators that compensate for the distortion voltage in the cable as well as provide voltage regulation in order to insure a voltage with the proper amplitude is received by the load.
The present invention compensates for the harmonic voltage drop across the cable which separates the line voltage regulator and the load by predistorting the voltage at the output of the regulator by the same amount as the voltage drop across the cable, but with opposite polarity and without sensing the voltage at the load. The present invention also compensates for the fundamental voltage drop across the cable and regulates the voltage as applied to a load. Therefore, the resulting voltage is distortion free as well as regulated as applied to the load and requires no sensing of the voltage at the load.